LED driving apparatus, method for driving LED, and display apparatus thereof

Abstract

A display apparatus is provided. The display apparatus includes a display panel which displays an image, a LED module which provides backlight to the display panel, a LED driving unit which selectively uses current of an inductor to apply driving voltage to the LED module, a sensing unit which senses a current value of the inductor, and a switching control unit which adjusts the driving voltage according to sensing result by the sensing unit.

What is claimed is:  
     
       1. A display apparatus comprising:
 a display panel which displays an image; 
 a light emitting diode (LED) module, which provides backlight to the display panel; 
 a LED driving unit, which selectively uses current of an inductor to apply a driving voltage to the LED module; 
 a sensing unit which senses a current value of the inductor; and 
 a switching control unit which applies the driving voltage according to a sensing result of the sensing unit, 
 wherein the LED driving unit includes a transistor connected to the inductor, 
 wherein the sensing unit includes a first comparator which compares the current value of the inductor with a predetermined first reference value and a first AND gate which performs a logic product of an inversion gate signal regarding a gate signal applied to a gate of the transistor and a comparison result of the first comparator and outputs a result of the logic product. 
 
     
     
       2. The apparatus as claimed in  claim 1 , wherein the LED driving unit applies the driving voltage to the LED module while exciting the inductor using a current input from an external power source or the LED driving unit applies driving voltage to the LED module using current induced by the excited inductor. 
     
     
       3. The apparatus as claimed in  claim 2 ,
 wherein the switching control unit turns on or off the transistor according to the sensing result by the sensing unit, applies the driving voltage to the LED module while exciting the inductor using the current input from the external power source when the transistor is turned on, and applies the driving voltage to the LED module using the current induced by the excited inductor when the transistor is turned off. 
 
     
     
       4. The apparatus as claimed in  claim 3 , wherein the switching control unit turns on the transistor when the current value sensed by the sensing unit is the predetermined first reference value, and turns off the transistor when the current value sensed by the sensing unit is a predetermined second reference value,
 wherein the predetermined second reference value is greater than the predetermined first reference value. 
 
     
     
       5. The apparatus as claimed in  claim 3 , wherein the LED driving unit comprises:
 an input terminal which receives the external power source; 
 a first capacitor which connects the input terminal to ground; 
 a first diode which connects a first end of the inductor to the input terminal; and 
 a second capacitor which connects a second end of the inductor to the input terminal, 
 wherein the LED module is connected to the second capacitor in parallel, and 
 wherein a connection node between the inductor and the diode is connected to a first end of the transistor. 
 
     
     
       6. The apparatus of  claim 2 , wherein the LED driving unit comprises an input terminal which receives an input voltage, a first diode which connects a first end of the inductor to the input terminal, and a capacitor which connects a second end of the inductor to the input terminal. 
     
     
       7. The apparatus of  claim 2 , wherein
 the switching control unit turns on the transistor when the current value sensed by the sensing unit is the predetermined first reference value and turns off the transistor when the current value sensed by the sensing unit is a predetermined second reference value. 
 
     
     
       8. A light emitting diode (LED) driving apparatus which controls a LED module, the apparatus comprising:
 a LED driving unit which selectively uses current of an inductor to apply a driving voltage to the LED module; 
 a sensing unit which senses a current value of the inductor; and 
 a switching control unit which adjusts the driving voltage according to a sensing result of the sensing unit, 
 wherein the LED driving unit includes a transistor connected to the inductor, 
 wherein the sensing unit comprises: 
 a first comparator which compares the current value of the inductor with a predetermined first reference value; and 
 a first AND gate which performs a logic product of an inversion signal regarding a gate signal applied to a gate of the transistor and a comparison result of the first comparator and outputs a result of the logic product. 
 
     
     
       9. The apparatus as claimed in  claim 8 , wherein the LED driving unit applies the driving voltage to the LED module while exciting the inductor using current input from an external power source or the LED driving unit applies driving voltage to the LED module using current induced by the excited inductor. 
     
     
       10. The apparatus as claimed in  claim 9 ,
 wherein the switching control unit turns on or off the transistor according to the sensing result by the sensing unit, applies the driving voltage to the LED module while exciting the inductor using current input from the external power source if the transistor is turned on, and applies the driving voltage to the LED module using current induced by the excited inductor if the transistor is turned off. 
 
     
     
       11. The apparatus as claimed in  claim 10 , wherein the switching control unit turns on the transistor when the current value sensed by the sensing unit is a the predetermined first reference value and turns off the transistor when the current value sensed by the sensing unit is a predetermined second reference value,
 wherein the second predetermined reference value is greater that the predetermined first reference value. 
 
     
     
       12. The apparatus as claimed in  claim 10 , wherein the LED driving unit comprises:
 an input terminal which receives the input voltage; 
 a first diode which connects a first end of the inductor to the input terminal; and 
 a capacitor which connects a second end of the inductor to the input terminal, 
 wherein the LED module is connected to the capacitor in parallel; 
 wherein a connection node between the inductor and the diode is connected to a first end of the transistor. 
 
     
     
       13. A LED driving method to control a LED module, the method comprising:
 sensing a value of a current of an inductor connected to the LED module; and 
 applying a driving voltage to the LED module using an external power source or the inductor excited by the external power source according to a result of the sensing, wherein the inductor is connected to a transistor; and 
 wherein the sensing the value of the current of the inductor comprises comparing the current value of the inductor with a predetermined first reference value using a first comparator, performing a logic product of an inversion gate signal regarding a gate signal applied to a gate of the transistor connected to the inductor and a comparison result of the first comparator using a first AND gate and outputs a result of the logic product. 
 
     
     
       14. The method as claimed in  claim 13 , wherein the applying the driving voltage to the LED module comprises applying the driving voltage to the LED module while exciting the inductor using current input from the external power source or applying driving voltage to the LED module using current induced by the excited inductor. 
     
     
       15. The method as claimed in  claim 13 , wherein the sensing comprises sensing whether the current value of the inductor is the predetermined first reference value or a second reference value,
 wherein the second reference value is greater than the first reference value. 
 
     
     
       16. The method as claimed in  claim 15 ,
 wherein the applying driving voltage to the LED module comprises: 
 turning on or turning off the transistor according to the result of the sensing by the sensing unit, 
 applying the driving voltage to the LED module by turning on the transistor while exciting the inductor using current input from an external power source when the current value of the inductor is the predetermined first reference value, and applying the driving voltage to the LED module by turning off the transistor using current induced by the excited inductor when the current value of the inductor is the second reference value.